xml2ucm: Prelude.head: empty list

[grbesd1]

Hi,
I'm trying to get HiFi UCM for audio codec.

https://github.com/jacoghi/android_device_xiaomi_markw/blob/master/audio/mixer_paths_wcd9335.xml

https://github.com/jacoghi/android_device_xiaomi_markw/blob/master/audio/audio_policy_configuration.xml

stack exec -- xml2ucm -m examples/mixer_paths_wcd9335.xml -c examples/audio_policy_configuration.xml -o examples

I kept both xml file example directory but i'm getting

xml2ucm: Prelude.head: empty list

Do mind what could be the issue?